Method and device for purifying the flue gases of a sintering process of ores and/or other material-containing materials in metal production

Abstract

A method for purifying waste gases of an at least partially burnt solid fuel to reduce pollutants such as SO x and/or HCl and NO x . The waste gas flows into a moving bed reactor from below through a lower and upper layer of an adsorption and/or absorption agent already polluted with NO x , SO x and/or HCl. SO x and/or HCl components are adsorbed from the waste gas into the NO x loaded adsorption and/or absorption agent. Thereafter, the waste gas is mixed with an ammonium-containing compound and flows through an upper horizontal gas inflow and bulk material removal tray of the moving bed reactor into the upper layer of the adsorption and/or absorption agent already polluted with NO x and small quantities of SO x and/or HCl. During the throughflow of the upper layer, NO x components are adsorbed from the waste gas onto the adsorption/absorption agent.

1. A method for purification of waste gas of an at least partially burnt solid fuel, said waste gas containing one or more gasses selected from the group consisting of CO 2 , CO, O 2 , H 2 O, and/or N 2 , and one or more pollutants selected the group consisting of NO x , SO x , HCl, HS, Hg, dioxins, furans, dusts, sublimatable residues, condensable residues, heavy hydrocarbons, and heavy metals, characterized in that:
 said waste gas flows into a moving bed reactor from below through a lower horizontal gas inflow and a bulk material removal tray of said moving bed reactor, into a lower layer of adsorption and/or absorption agent already polluted with NO x  and SO x  and/or other pollutants, and with a throughflow of said lower adsorption agent and/or absorption agent layer, adsorbs at least a main quantity of SO x  from said waste gas in a pore system of said adsorption and/or absorption agent, loaded with NO x  and/or N 2 ; 
 said waste gas, purified of said main quantity of SO x  leaves said lower adsorption and/or absorption agent layer on its upper free surface, so as to be intimately mixed subsequently for conversion of said NOx, with an ammonium-containing compound; 
 said waste gas, mixed with said ammonium-containing compound and purified of said main quantity of SO x , enters from below through an upper horizontal gas inflow and said bulk material removal tray of said moving bed reactor, an upper layer of said adsorption and/or absorption agent already polluted with NO x  and/or N 2 , with a throughflow of said upper adsorption and/or absorption agent layer, adsorbs at least a main quantity of NO x    
 
       components from said waste gas and/or their reaction products, on a surface of said and/or absorption agent, loaded with NO x  and/or N 2 ;
 said waste gas, purified of said main quantity of SO x  leaves said upper adsorption and/or absorption agent layer on its upper free surface, so as to subsequently leave said process; 
 fresh and/or regenerated adsorption and/or absorption agent is supplied to said upper free surface of said upper layer of said adsorption and/or absorption agent, uniformly distributed from above via a bulk material-distributing tray, on said upper end of said moving bed reactor and without interruption by blocking elements in an area of said upper gas inflow and said bulk material removal tray, subsequently migrates completely through said upper and lower layers of said entire moving bed reactor, gradually, from above downwards, and thereby successively, is initially loaded with NO x  or N 2  and water vapor on its surface, and subsequently with SO x  in its pore system, and subsequently migrates through a lower gas inflow and said bulk material removal tray of said moving bed reactor; 
 said subsequent conducting, removal, and said migration rate of said adsorption agent and/or said absorption agent takes place via bulk material discharge elements, below or on said lower gas inflow and said bulk material removal tray; and, 
 a loading quantity of said adsorption and/or absorption agent in said upper layer of said moving bed reactor with SO x  is adjusted to a pre-specifiable quantity fraction, relative to said loaded adsorption and/or absorption agent, by a corresponding actuation of said bulk material discharge elements, below or on said lower gas inflow and said bulk material removal tray. 
 
     
     
       2. The method as defined in  claim 1 , wherein a loading value of said adsorption and/or absorption agent of said moving bed reactor in said upper layer with SO x  is limited to a maximum 10 wt % relative to a weight of said adsorption and/or absorption agent, removed on said bulk material discharge elements. 
     
     
       3. The method as defined in  claim 1 , wherein a carbon-containing adsorption and/or absorption agent is used as said adsorption and/or absorption agent. 
     
     
       4. The method as defined in  claim 3 , wherein said carbon-containing adsorption and/or absorption agent is an active coke. 
     
     
       5. The method as defined in  claim 3 , wherein said carbon-containing adsorption and/or absorption agent has a particle size of predominantly 1 mm to 10 mm. 
     
     
       6. The method as defined in  claim 3 , wherein said consumed or partially consumed adsorption and/or absorption agent, removed below from said moving bed reactor, is extensively freed in a regeneration step, from said adsorbed and/or absorbed pollutants and at least partially is delivered once again above to said moving bed reactor as said adsorption and/or absorption agent alone or mixed with said freshly used, carbon-containing adsorption and/or absorption agent. 
     
     
       7. The method as defined in  claim 6 , wherein said regeneration step takes place in a 3-stage process in which said nitrogen-loaded active coke is initially guided from said moving bed reactor in a vertically extended regeneration unit, from above, through an indirectly heated desorber and subsequently is conducted from above, through a post-degassing zone, with suctioning of desorbed polluting gas, and finally, from above, through an indirectly cooled cooler. 
     
     
       8. The method as defined in  claim 3 , wherein as said freshly used, carbon-containing adsorption and/or absorption agent, a preactivator is used. 
     
     
       9. The method as defined in  claim 3 , wherein said gas purification takes place on said adsorption and/or absorption agent, at temperatures above 80° C. 
     
     
       10. The method as defined in  claim 3 , wherein said upper layer of said adsorption and/or absorption agent has, in the moving bed reactor, a height between 1.5 m and 4.5 m. 
     
     
       11. The method as defined in  claim 3 , wherein said lower layer of said adsorption and/or absorption agent has, in said moving bed reactor, a height between 0.5 m and 3 m. 
     
     
       12. The method as defined in  claim 1 , wherein an ammonium-containing compound is produced, for said NO x  conversion and adsorption on a bulk material, from a mixture of an ammonium-containing solution and compressed air, said mixture of which is atomized into an evaporator, with an air/H 2 O-vapor/NH 3  gas mixture, with an admixture of a another heated mixture of an ammonium-containing solution and air. 
     
     
       13. The method as defined in  claim 1 , wherein a substance selected from the group consisting of calcium oxide, calcium hydroxide, sodium bicarbonate, alkali-earth compound, and alkaline-earth compound for binding of a partial quantity of said SO x , HS, and/or HCl is added to said waste gas in a preliminary purification step. 
     
     
       14. The method as defined in  claim 13 , wherein said added quantity corresponds to a stoichiometry factor between 1.0 and 2.5. 
     
     
       15. The method as defined in  claim 13 , wherein a partial quantity of the SO x , and/or HCl is removed in a preliminary purification stage corresponds to a fraction between 10 and 90% of said SO x , HS, and/or HCl contained in said waste gas. 
     
     
       16. The method as defined in  claim 1 , wherein a partial quantity of the SO x , and/or HCl is removed in a preliminary purification stage corresponds to a fraction between 10 and 90% of said SO x , and/or HCl contained in said waste gas. 
     
     
       17. An apparatus for the purification of waste gas of an at least partially burnt solid fuel, wherein said waste gas contains one or more gasses selected from the group consisting of CO 2 , CO, O 2 , H 2 O and N 2 , and one or more pollutants selected from the group consisting of NO x , SO x , HCl, Hg, dioxins, furans, dusts, and sublimatable residues, condensable residues, heavy hydrocarbons, and heavy metals; characterized by:
 a moving bed reactor, tilled with a lower and an upper adsorption agent and/or absorption agent layer, with a lower horizontal gas inflow and a bulk material removal tray, through which said waste gas can flow from below into a lower layer of said adsorption and/or absorption agent already polluted with NO x , and/or N 2 , and SO x ; 
 a mixing element, subsequently inserted on an upper free surface of said lower adsorption and/or absorption agent layer, for intimate mixing of said waste gas, purified of a main quantity of SO x , with an ammonium-containing compound; 
 an upper, horizontal gas inflow and said bulk material removal tray of said moving bed reactor, without blocking elements in an area of upper gas inflow and said hulk material removal tray, through which said waste gas, mixed with said ammonium-containing compound and purified of said main quantity of SO x  can flow from below, into said upper layer of said adsorption and/or absorption agent already polluted with NO x  or N 2  and small quantities of SO x ; 
 an upper free surface of said upper adsorption and/or absorption agent layer from which said waste gas, purified of said main quantity of SO x  and NO x  components, can leave said adsorption and/or absorption layer, so as to subsequently leave said moving bed reactor; 
 a bulk material-distributing tray on said upper end of said moving bed reactor that can be supplied by fresh and/or regenerated adsorption and/or absorption agent, via said upper free surface of said upper layer of said adsorption agent and/or absorption agent, from above; 
 bulk material discharge elements, on or below said lower gas inflow and said bulk material removal tray, taking place by subsequent conducting, removal, and migration rate of said adsorption and/or absorption agent; and, 
 control means of said bulk material discharge elements, by means of which a loading quantity of said adsorption and/or absorption agent in said upper layer of said moving bed reactor can be adjusted with SO x  to a pre-specifiable quantity fraction, relative to said loaded adsorption and/or absorption agent, by corresponding actuation of said bulk material discharge elements, below or on said lower gas inflow and said bulk material removal tray. 
 
     
     
       18. The apparatus as defined in  claim 17 , wherein said mixing element for said intimate mixing of said waste gas, purified of said main quantity of SO x , with said ammonium-containing compound comprises a slit nozzle, which extends approximately horizontal over at least one wall side of said moving bed reactor. 
     
     
       19. The apparatus as defined in  claim 17 , wherein an NH 3  addition unit, with which ammonium-containing compound for the NO x  conversion and adsorption on a bulk material is produced, with a mixing site for an ammonium-containing solution, a heat exchanger for heating of another mixture of an ammonium-containing solution and air, and with a nebulization nozzle for admixing of a first mixture to a heated second mixture in an evaporator, with formation of an air/H 2 O-vapor/NH 3  mixture. 
     
     
       20. The apparatus as defined in  claim 17 , wherein a regeneration unit for a 3-stage desorption process, in which pollutant-loaded active coke is initially guided from said moving bed reactor of a vertically extended regeneration unit from above through an indirectly heated desorber, and subsequently is conducted from above through a post-degassing zone, with suctioning-off of desorbed polluting gas, and finally, from above, through an indirectly cooled cooler. 
     
     
       21. A method for the purification of waste gas that contains one or more gasses selected from the group consisting of CO 2 , CO, O 2 , H 2 O and N 2 , and one or more pollutants selected from the group consisting of NO x , SO x , HCl, HS, Hg, dioxins, furans, dusts, sublimatable residues and condensable residues, heavy hydrocarbons, and heavy metals, said method including the steps of:
 a. flowing said waste gas into a moving bed reactor from below through a lower horizontal gas inflow and bulk material removal tray of the moving bed reactor, into a lower layer of adsorption and/or absorption agent already polluted with NO x  and SO x  and/or other pollutants, and with a throughflow of a lower adsorption agent and/or absorption agent layer, adsorbs at least a main quantity of SO x  from said waste gas in a pore system of said adsorption an/or absorption agent, loaded with NO x  and/or N 2 ; 
 b. removing said waste gas from said lower adsorption and/or absorption agent layer on its upper free surface so as to be intimately mixed subsequently for conversion of said NO x  with ammonium-containing compound; 
 c. flowing said waste gas that is mixed with said ammonium-containing compound and purified of said main quantity of SO x  from below through an upper horizontal gas inflow and a bulk material removal tray of said moving bed reactor, an upper layer of said adsorption and/or absorption agent already polluted with NO x , N 2  and/or SO x  with throughflow of said upper adsorption and/or absorption agent layer, adsorbs at least a main quantity of NO x  components from said waste gas and/or their reaction products, on a surface of said adsorption and/or absorption agent, loaded with NO x  N 2  and/or SO x ; 
 d. removing said waste gas that is purified of said main quantity of SO x  and NO x  components from said upper adsorption and/or absorption agent layer on its upper free surface, so as to subsequently leave said process; 
 e. supplying fresh and/or regenerated adsorption and/or absorption agent to said upper free surface of said upper layer of said adsorption and/or absorption agent, via a bulk material-distributing tray, on the upper end of said moving bed reactor and without interruption by blocking elements in an area of upper gas inflow and said bulk material removal tray, subsequently migrates completely through said upper and lower layers of said entire moving bed reactor, gradually, from above downwards, and thereby successively, is initially loaded with NO x  or N 2  and water vapor on its surface, and subsequently with SO x  in its pore system, and subsequently migrates through a lower gas inflow and said bulk material removal tray of said moving bed reactor, a subsequent conducting, removal, and migration rate of said adsorption agent and/or said absorption agent takes place via bulk material discharge elements, below or on said lower gas inflow and said bulk material removal tray; and, 
 f. loading a quantity of said adsorption and/or absorption agent in said upper layer of said moving bed reactor with SO x  is adjusted to a pre-specifiable quantity fraction, relative to said loaded adsorption and/or absorption agent, by corresponding actuation of said bulk material discharge elements, below or on said lower gas and said bulk material removal tray.